Phonophoresis (also known as sonophoresis or ultrasonophoresis) is the movement of a medicament through the skin by the application of sonic radiation to the medicament placed upon the skin. Although the technique has been well known in the field of physical therapy for some time, widespread application has been hindered by the requirement for supervision during the application of the ultrasonic radiation, and by the use of relatively large physical therapy machines for the application of that radiation
Recently developed polymeric materials exhibiting piezoelectric properties now make possible a new generation of phonophoretic applicators which bypass any of the problems inherent in drug delivery using conventional transducers. Of these polymers, polyvinylidene fluoride (PVDF) is most readily available, but there are other polymeric materials which exhibit piezoelectric effects, and hybrid ceramic compositions in a polymer matrix have the characteristic of being flexible rather than brittle, and in quantity are much less expensive than conventional piezoceramics
In addition to drug delivery, another broad application area for ultrasonics is in improved wound healing, because it has been well established that ultrasound by itself can speed up the healing process in open wounds Finally, not only can piezoelectric polymeric materials enhance drug delivery by conventional phonophoretic techniques, but also they can present the potential for totally new applications of sonic energy in improved drug delivery and sound heating. The large coupling between thickness and longitudinal modes (d.sub.31) in such piezoelectric polymers, combined with the ability to make very long, thin elements from them, provides the opportunity to create bandages which can act upon the skin in new ways.
The present invention relates to bandage assemblies for phonophoresis of medicaments, and, more particularly, to a bandage assembly having piezoelectric components which contains a medicament to be phonophoretically transferred into a patient upon which it is placed.
in the broadest sense, the bandage provides a means for application of sonic energy to the skin by means of nonconventional polymeric sonic generators. The sonic energy may be applied in the conventional way, using the piezoelectric generator in the thickness mode, and it may also be applied as a stretching of the skin by driving the polymer in a thickness-longitudinal mode or it may be applied by a bimorph bender. It may be applied by a combination of the preceding depending on the type of medicament, the type of skin and the frequencies employed. The different elements that make up the sonic generator may be activated either at a single frequency, or at multiple frequencies applied simultaneously. The sonic energy may be applied either in continuous wave mode or in a burst mode.
Accordingly, it is an object of the present invention to provide a novel bandage assembly using piezoelectric polymers for percutaneous administration of medicaments.
It is also an object to provide such a bandage assembly which may be readily fabricated and which can utilize the sonic vibrations to stretch the skin as well as to drive the medicament therethrough.
Another object is to provide such an assembly in which the assembly may be utilized over an extended period of time to effect intermittent, or controlled rate, administration of the medicament.
A further object is to provide such an assembly which utilizes a compact and self-contained sonic generator which may be readily coupled to disposable bandage members.